couple of things.. first... it is going to be extremely difficult to get a good fitting screen protector for a curved screen. Even on something with more subtle curves, like a "2.5D" screen, you aren't going to get edge to edge coverage. Samsung's curved screens are a nightmare to design for, especially for tempered glass.
As for if you need them.... You don't. The glass is fairly resilient, but it is still glass. All it takes is a few grains of sand in your pocket, etc, and that sucker will get scratched up right good. Fact is that the world is filled with bits of stuff that will mark up your screen, either with fine scratches you may only see when the light hits it just so, or a substantial gouge that you can see no matter what. If you are OK with that, go without.
When my wife had her S7 Edge, I couldn't for the life of me get a protector that a) fit and b) didn't look like junk. I ended up leaving it naked. I dumped it about 6 months later and it had a few fine scratches but otherwise was in good condition. But scratch is scratch... and if I can spend a small amount of money to put on a good fitting and unobtrusive screen protector, I'll take that over the alternative every day of the week.